1. Field of the Invention
The present invention relates to a visual field agreement type information presentation system in which information related to an image photographed by image pickup means is superimposed on the photographed image and simultaneously displayed in a limited specific district and in which the information can be presented at a high density by an image observer, and a portable information terminal and server for use in the system.
2. Description of the Related Art
A calculation technique using a plurality of markers to obtain position and orientation information of image pickup means has heretofore been proposed.
For example, in Jpn. Pat. Appln. KOKAI Publication No. 2001-126051,a method is proposed comprising: reading information included in a reference marker in order to obtain a schematic position and orientation of an image acquisition section, so that positions of the reference marker and a marker disposed around the reference marker and/or a characteristic point can be confirmed. According to the technique disclosed in the publication, the positions of four or more markers and/or the characteristic point are confirmed, and this information can be used to estimate the position and orientation of the image pickup means.
Moreover, a method of obtaining the position/orientation of the image pickup means from the reference marker position is disclosed in “A High Accuracy Realtime 3D Measuring Method of Marker for VR Interface by Monocular Vision” (3D Image Conference '96 Proceeding pp. 67-172,Akira Takahashi, Ikuo Ishii, Hideo Makino, Makoto Nakashizuka, 1996). That is, assuming in FIG. 1 that Oc is a visual point, p0 is a projected image diagonal line intersection, and P0 is a rectangle diagonal image intersection, x′ is obtained so as to minimize:
      F    ⁡          (              x        ′            )        =      4    -                  ∑                  i          =          1                4            ⁢                        (                                    n              i                        ⁢                          n              i              ′                                )                2            so that the orientation of the image pickup means is obtained. It is to be noted that here a variable vector x′ is x′=(α1′β1′, α2′). For the position of the image pickup means, minimum square estimation of d for minimizing a distance between Ocpi and vertex Pi is performed.
  d  =                                          (                                          s                0                            ⁢                              s                i                                      )                    ⁢                      (                                          s                i                            ⁢                              w                i                                      )                          -                  (                                    s              0                        ⁢                          w              i                                )                            1        -                              (                                          s                0                            ⁢                              s                i                                      )                    2                      ⁢    D  
Next, the position of the image pickup means can be determined by an average of depth values obtained from the respective vertices.
Moreover, in “Mixed Reality” (ISBN 4-274-90283-8 Ohmsha, Ltd.) Chapter 6:“Augmented Reality Tracking in Natural Feature Environments” U. Nehmann, S. You, Y. Cho, J. Lee and J. Park 1999 p.101-130,a known reference point called a “Fiducial Mark” is used to obtain an initial position of the image pickup means. In this case, a plurality of characteristic points is extracted to obtain a projected position in an input image. The characteristic point is tracked in response to movement of an input device, and an optimum solution of the position of the image pickup means is obtained.
On the other hand, many attractions or exhibits are usually scattered in specific districts such as an amusement park, theme park, and museum. Therefore, to directly visit the objective attraction or exhibit, a general visitor employs a method of consulting a booklet map distributed by a company managing the specific district or a guide map in a main passageway to search a destination.
Moreover, for shopping in a souvenir shop in the specific district, it is usual to visit the shop and to buy articles over the counter. In recent years, information indicating the shop and the articles dealt in by the shop can be obtained beforehand by guidebooks, but in actual the articles are usually bought only over the counter.